1. Field of the Invention
The present invention relates generally to displaying information in three dimensions, and in particular, to a method, apparatus, and article of manufacture for providing three dimensional (3D) depth cues for selected data.
2. Description of the Related Art
In computer applications, graphical user interfaces often display visual cues that indicate the selection of data such as text, lines, graphical objects, etc. Such visual cues assist the user in editing and manipulating the data. In three-dimensional space, it becomes more difficult to indicate that data has been selected. Such problems may be better understood by describing three-dimensional computing and visual cues used in the prior art.
When a computer user is editing data (of a variety of forms), the user will frequently desire to select a particular data object/unit to perform an edit operation on. Some examples include selecting text in a word processing application to under line the text, selecting a line in a drawing program (e.g., Autodesk AutoCAD) to change its color, or selecting a cell in a spreadsheet program to edit/copy. When performing these selections, the computer program provides visual cues/feedback, referred to as highlighting, to the user to identify the data that has been selected. The predominant use of highlighting is to mark selections. However, highlighting can also be used to focus a user's attention on the highlighted data, even if that highlighted data is not going to be edited.
Prior art visual cues and highlighting may take many forms. For example, the data's color may be inverted (e.g., white on black instead of black on white) using an exclusive OR (XOR) operation. Alternatively, the data's color may be brightened, dimmed, or just changed. In yet another alternative, the selected data may be displayed in a bold typeface.
One problem with such prior art techniques is that all of the approaches use visual attributes that are normally available for the data (i.e., attributes available to the data in the data's natural state). For example, text may already be bold or inverted as part of a document. Further, graphical lines may already be many different colors, brightness levels, or opacity in a drawing. Accordingly, the prior art highlighting may not be distinguishable or as distinguishable from the remaining non-selected data as desired.
Further, as graphical user interfaces become more sophisticated with more widespread use of additional available options, the display of highlighting using natural attributes of the data becomes less distinguishable. For example, hardware and software devices may track the movement of a user's eyes and utilize the tracked information to control the application or aspects of the application. Such tracking may utilize many displayable options that must be distinguishable to accurately track eye movement. In another example, hardware and software may simulate the display of information in 3D to provide additional options that may require a mechanism for more easily and clearly distinguishing selected data from other displayed data. To better understand the display of data in 3D, a review of the 3D technology is provided below.
To create a visual sensation of 3D, a two dimensional (2D) display must simulate various elements/attributes of a real 3D scene. Some of these attributes include geometric perspective, aerial perspective, and stereoscopy.
Geometric perspective provides for displaying data smaller and closer together as the data is farther away from the viewer. Geometric perspective is relatively easy to simulate requiring only the correct mathematical algorithms to render a 3D object with correct perspective. 3D accelerators may provide this functionality in typical computers.
An aerial perspective attribute provides for varying the color intensity and contrast for data and objects based on their distance from the user. For example, less intense color and contrast may be displayed for objects that are farther away. Since the colors of most objects are known, the human brain may use a change in color intensity and contrast to create a sensation of depth. Modern 3D accelerators may attempt to simulate aerial perspective using “fog” effects to dim the color intensity of distant surfaces.
A stereoscopy attribute manifests itself by the human brain interpreting differences between images presented to each eye and synthesizing the sensation of depth. Standard 2D computer displays cannot produce stereoscopic images without help. However, newer monitors and other hardware devices may provide such capabilities.
Many new display and hardware systems simulate one or more of the above 3D attributes. For example, a thin layer of special plastic may be placed between a lighted back panel and a LCD (liquid crystal display) of a monitor. Such a layer may be used to direct light rays from the backlight to the left and right eyes to create a stereoscopic view. Using the layer, alternate columns of image pixels are projected into the left and right eyes thereby resulting in two distinct stereoscopic images, one directed at the left eye, and one directed at the right eye. Such a technique provides one image to the right eye and a slightly different one to the left eye to simulate 3D. Other techniques may layer semi-transparent flat display screens. Additional hardware such as shutter glasses contain small LCD panels that cover each eye and images are shuttered between the left and right eye to provide a stereoscopic image.
Accordingly, various techniques and devices may be utilized to simulate three dimensions to a viewer. However, the problem with distinguishing selected data, whether in two dimensions or three dimensions remains. Further, such new techniques and devices are primarily used for modeling 3D data. Such techniques and devices lack the ability to interact with data (including 2D data) in a real-world, 3D fashion.